vfs: define struct filename and have getname() return it

getname() is intended to copy pathname strings from userspace into a
kernel buffer. The result is just a string in kernel space. It would
however be quite helpful to be able to attach some ancillary info to
the string.

For instance, we could attach some audit-related info to reduce the
amount of audit-related processing needed. When auditing is enabled,
we could also call getname() on the string more than once and not
need to recopy it from userspace.

This patchset converts the getname()/putname() interfaces to return
a struct instead of a string. For now, the struct just tracks the
string in kernel space and the original userland pointer for it.

Later, we'll add other information to the struct as it becomes
convenient.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/compat.c b/fs/compat.c
index b7a24d0ca30d..015e1e1f87c6 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -776,16 +776,16 @@ asmlinkage long compat_sys_mount(const char __user * dev_name,
         char *kernel_type;
         unsigned long data_page;
         char *kernel_dev;
-        char *dir_page;
+        struct filename *dir;
         int retval;
 
         retval = copy_mount_string(type, &kernel_type);
         if (retval < 0)
                 goto out;
 
-        dir_page = getname(dir_name);
-        retval = PTR_ERR(dir_page);
-        if (IS_ERR(dir_page))
+        dir = getname(dir_name);
+        retval = PTR_ERR(dir);
+        if (IS_ERR(dir))
                 goto out1;
 
         retval = copy_mount_string(dev_name, &kernel_dev);
@@ -807,7 +807,7 @@ asmlinkage long compat_sys_mount(const char __user * dev_name,
                 }
         }
 
-        retval = do_mount(kernel_dev, dir_page, kernel_type,
+        retval = do_mount(kernel_dev, dir->name, kernel_type,
                         flags, (void*)data_page);
 
  out4:
@@ -815,7 +815,7 @@ asmlinkage long compat_sys_mount(const char __user * dev_name,
  out3:
         kfree(kernel_dev);
  out2:
-        putname(dir_page);
+        putname(dir);
  out1:
         kfree(kernel_type);
  out: